Mix the flour, salt, sugar and yeast in a bowl. Add the butter, milk and egg, knead to form a soft, smooth dough. Cover and leave to rise at room temperature for approx. 2 hrs. until doubled in size, halve the dough.
Quarter one half of the dough, place the pieces of dough on a lightly floured surface, flatten then roll out to circles (approx. 25 cm diameter), place a circle of dough on a baking tray lined with baking paper. Spread 1/3 of the chocolate spread over the top, leaving a border of approx. 2 cm. Lay the 2nd circle of dough on top and cover with another 1/3 of the chocolate spread. Repeat this step once more. Lay the last circle of dough on top and press the edge down firmly.
Combine the jam with the lemon zest. Repeat with the second half of the dough, using jam in place of chocolate spread. Place a glass (approx. 8 cm diameter) in the centre of each piece of dough. Cut each section of dough into approx. 16 strips, up to the edge of the glass. Take two strands of dough that are next to each other and twist them twice 360 °C in opposite directions, then fold the ends into a heart shape. Brush the yeast dough stars with a little egg.
Each tray for approx. 25 mins. in the bottom half of an oven preheated to 180°C. Remove from the oven, slide onto a cooling rack and allow to cool. Dust with icing sugar.